1. Field of the Invention
The present invention relates to the fields of communications and networking. More particularly, the present invention relates to an in-band QoS signaling reference model for QoS-driven wireless networks.
2. Description of the Related Art
With the advent of digital broadband networks, such as hybrid fiber-coaxial networks and 3G/4G cellular networks, packetized multimedia services to residential and enterprise environments are becoming not only a reality, but also a necessity. Wireless delivery of, or access to, multimedia applications, such as voice, video and data, is considered viable for helping accelerate this trend.
The transport of multimedia traffic over a shared network generally requires specific levels of quality of service (QoS) support for achieving predictable and satisfactory network service. Technically, QoS refers to the expectation of a session or an application to receive, as well as the ability of a network to provide, a negotiated set of service values for data transmission in terms of delay/jitter bound, mean/maximum data rate, and the like. QoS is enforced and supported by such techniques as effective congestion control, adequate resource reservation, proper traffic shaping, and prioritized bandwidth allocation. With some degree of QoS guarantees, shared channels furnish time-bounded and asynchronous services that are comparable to those of dedicated channels.
Bandwidth utilization efficiency is another important consideration in the design of a multimedia network. High bandwidth utilization efficiency leads to increased channel throughput and reduced access delay, thereby permitting the same channel bandwidth to serve more sessions/applications with given QoS levels. In the case of bandwidth shortage, maximizing bandwidth utilization efficiency minimizes the degradation of QoS values provided to active sessions/applications.
Unfortunately, wireless local-area networks (WLANs), such as currently specified by IEEE P802.11/1999, do not support QoS transport and operate on a distributed contention or simplified polling basis. Consequently, only asynchronous and low-throughput best-effort data services are provided.
What is needed is a technique for transforming a WLAN into part of an end-to-end QoS network having enhanced channel access, thereby providing QoS support with improved bandwidth utilization.
The present invention provides an in-band QoS signaling reference model that can be used to extend the functionality of the architectural reference model of the invention. The advantages of the present invention are provided by a station, such as a point coordinator (PC) or a non-PC station, in a basic service set (BSS) in a wireless local area network (WLAN). According to the invention, the station includes a frame classification entity (FCE), a frame scheduling entity (FSE) and a QoS management entity (QME). The FCE is logically located in a logical link control (LLC) layer of the station and has a classification table containing at least one classifier entry. Each classifier entry contains a virtual stream identifier (VSID) and a frame classifier associated with a user session. The FCE receives a data frame associated with the user session, which can be one of a voice session, a video session, a data session and a multimedia session. The data frame contains in-band quality of service (QoS) signaling information for the user session. The FCE classifies the received data frame to a selected VSID contained in a classifier entry in the classification table based on a match between an in-band frame classification information contained in the received frame and the frame classifier contained in the classifier entry. The FSE is logically located in a medium access control (MAC) sublayer of the station and has a frame scheduling table containing at least one entry. Each entry in the frame scheduling table contains a VSID and a QoS parameter set associated with a user session identified by the VSID. The FSE is responsive to the classified data frame by scheduling a transmission opportunity (TO) for the classified data frame based on the at least one QoS parameter value associated with the VSID and characterizing the user session. The QME interfaces with the FCE and The FSE. When the FCE cannot classify the received data frame, the FCE passes the received data frame to the QME and the QME examines the data frame for obtaining a frame classifier and at least one QoS parameter value characterizing a new user session.
When the station is a PC station, the QME of the PC station establishes a virtual down-stream (VDS) for transporting the traffic of the user session from the LLC sublayer entity of the PC station to at least one peer LLC sublayer entity in the BSS, and assigns a VSID to the established VDS. The QME then passes the VSID and the frame classifier associated with the new user session to the FCE, and the FCE adds the VSID and the frame classifier to a new classifier entry in the classification table. The QME also passes the VSID and the at least one QoS parameter value associated with the new user session to the FSE. The FSE adds the VSID and the at least one QoS parameter value to a new entry in the frame scheduling table. The QME causes the PC station to send a management frame containing the VSID associated with the new user session and indicating the management frame being for adding the new VDS to each non-PC station that is to receive the new user session in the BSS.
When the station is a non-PC station in the BSS, the QME causes the non-PC station to send a management frame to the PC station of the BSS. In this case, the management frame contains a special VSID, a frame classifier, at least one QoS parameter value that are associated with the new user session, and an indication that the management frame is for setting up the new user session. When the PC station receives the management frame, the information contained in the management fame is passed to the QME of the PC station. The QME of the PC station then establishes one of a virtual up-stream and a virtual side-stream (VUS/VSS) for transporting the traffic of the user session from the LLC sublayer entity of the non-PC station to at least one peer LLC sublayer entity in the BSS, and assigns a VSID to the established VUS/VSS. The QME of the PC station also passes the VSID and the at least one QoS parameter value associated with the new user session to the FSE of the PC station. In response, the FSE of the PC station adds the VSID and the at least one QoS parameter value to the new entry in the frame scheduling table. The QME of the PC station causes the PC station to return a management frame containing the VSID, the frame classifier and the at least one QoS parameter value that are associated with the new user session to the non-PC station that sent a management frame to the PC station. The return management frame includes an indication for adding the new VUS/VSS. When the non-PC station receives the return management frame, the information contained in the return management frame is passed to the local QME. The local QME of the non-PC station passes the VSID and the frame classifier contained in the management frame to the local FCE, and the local FCE adds the VSID and the frame classifier to a new classifier entry in the local classification table. The QME of the non-PC station also passes the VSID and the at least one QoS parameter value contained in the management frame to the local FSE. In response, the local FSE adds the VSID and the at least on QoS parameter value to a new entry in the local scheduling table.
According to one aspect of the invention, the FCE includes a timer value for each classifier entry in the classification table, and when the FCE successfully classifies the received frame to a selected VSID contained in a classifier entry of the classification table, the FCE sets the timer value corresponding to the classifier entry to a predetermined value. The timer value for the classifier entry expires when no data frame associated with a user session using the classifier entry is successfully classified by the FCE. When the timer value for the classifier entry expires, the FCE deletes the classifier entry and passes the VSID in the classifier entry to the QME of the station, and the QME instructs the FSE to remove the entry containing the VSID from the scheduling table maintained in the station. When the station is the PC station in the BSS, the QME causes the PC station to send a management frame containing the VSID associated with the user session and an indication that the management frame is for deleting the user session to each non-PC station receiving the user session in the BSS. When the station is a non-PC station in the BSS, the QME causes the non-PC station to send a management frame containing the VSID associated with the user session and an indication that the management frame is for deleting the user session to the PC station in the BSS. When the PC station receives the management frame, the information contained in the management frame is passed to the QME of the PC station. The QME of the PC station then instructs the FSE of the PC station to delete the entry containing the VSID contained in the management frame from the scheduling table maintained in the PC station.